diff --git a/packages/nagstamon.nix b/packages/nagstamon.nix
index a20cd9c..451efd1 100644
--- a/packages/nagstamon.nix
+++ b/packages/nagstamon.nix
@@ -1,6 +1,6 @@
-{ stdenv, fetchFromGitHub, python37Packages, wrapQtAppsHook }:
+{ stdenv, fetchFromGitHub, python39Packages, wrapQtAppsHook }:
 
-python37Packages.buildPythonApplication rec {
+python39Packages.buildPythonApplication rec {
   pname = "nagstamon";
   version = "3.7.0-alpha";
 
@@ -20,7 +20,7 @@ python37Packages.buildPythonApplication rec {
     wrapQtApp $out/bin/nagstamon.py
   '';
 
-  propagatedBuildInputs = with python37Packages; [
+  propagatedBuildInputs = with python39Packages; [
     beautifulsoup4
     configparser
     dateutil